test: refactor test-net-nodejsGH-5504

* Improve comments describing test.
* Remove unnecessary `common.noop`
* Remove confusing scoping of `c` identifier

PR-URL: nodejs#13025
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/sequential/test-net-GH-5504.js

@@ -22,11 +22,13 @@
 'use strict';
 const common = require('../common');
 
-// this test only fails with CentOS 6.3 using kernel version 2.6.32
-// On other linuxes and darwin, the `read` call gets an ECONNRESET in
+// Ref: https://github.com/nodejs/node-v0.x-archive/issues/5504
+//
+// This test only fails with CentOS 6.3 using kernel version 2.6.32.
+// On other Linuxes and macOS, the `read` call gets an ECONNRESET in
 // that case.  On sunos, the `write` call fails with EPIPE.
 //
-// However, old CentOS will occasionally send an EOF instead of a
+// However, old CentOS will occasionally send an EOF instead of an
 // ECONNRESET or EPIPE when the client has been destroyed abruptly.
 //
 // Make sure we don't keep trying to write or read more in that case.
@@ -74,25 +76,24 @@ function parent() {
       NODE_DEBUG: 'net'
     })
   });
-  let c;
 
   wrap(s.stderr, process.stderr, 'SERVER 2>');
   wrap(s.stdout, process.stdout, 'SERVER 1>');
-  s.on('exit', common.mustCall(common.noop));
+  s.on('exit', common.mustCall());
 
   s.stdout.once('data', common.mustCall(function() {
-    c = spawn(node, [__filename, 'client']);
+    const c = spawn(node, [__filename, 'client']);
     wrap(c.stderr, process.stderr, 'CLIENT 2>');
     wrap(c.stdout, process.stdout, 'CLIENT 1>');
-    c.on('exit', common.mustCall(common.noop));
+    c.on('exit', common.mustCall());
   }));
 
   function wrap(inp, out, w) {
     inp.setEncoding('utf8');
-    inp.on('data', function(c) {
-      c = c.trim();
-      if (!c) return;
-      out.write(`${w}${c.split('\n').join(`\n${w}`)}\n`);
+    inp.on('data', function(chunk) {
+      chunk = chunk.trim();
+      if (!chunk) return;
+      out.write(`${w}${chunk.split('\n').join(`\n${w}`)}\n`);
     });
   }
 }